Field
Embodiments of the present disclosure generally relate to apparatus and methods for monitoring and controlling filaments used in hotwire semiconductor processing.
Description of the Related Art
Hotwire semiconductor processes generally involve decomposing precursor gases on heated filaments. For example, in hotwire chemical vapor deposition (HWCVD) and hotwire etch, radical species in the decomposed precursor gases often react in the gas phases and deposit onto or etch into a heated substrate.
During hotwire processes, hotwire temperature, among others, is usually monitored and controlled to obtain desired process quality. However, determining temperature of the hotwire filament is challenging because of the temperature range of the filament is high, e.g. higher than 1500° C., and morphology of the filament assembly. Infrared pyrometry and thermocouples are conventionally used for the measuring temperature of the hotwire filament. However, infrared pyrometry is not only costly but also prone to inaccuracy because the infrared pyrometers are unable to capture the temperature of the entire filament assembly. Thermocouples also cannot achieve accurate temperature measurement because thermocouples can only measure a limited number of measuring points where isolation and sensitive manual placement requirement can be satisfied.
Therefore, there is a need for improved temperature measurement for hotwire filaments.